Yes, My Kindle Can Do This: Flappy Bird on Paper

Yes, I’m bad. You can try to do better on the live demo. You will need to print (or display on your favourite device) this tag. The demo needs to access your webcam via the getUserMedia/Stream API, which means it works only on Firefox, Chrome and Opera. It should work on their mobile versions though. Firefox has the best performances, thanks to the asm.js optimisations.

How does it work ?

When Chilitag number 8 (why 8? no idea) is detected, the bird flaps. If the tag was continuously detected, the bird would take off like a rocket, so users naturally make flapping movements with their hand. This has been observed in 100% of the users at the time of this writing (I was alone).